The invention relates to a submersible fish cage, submersible to protect the cage and its contents of live marine organisms against undesired environmental agents as strong waves, ice formation, oil pollution and similar effects.
The applicants have since 1989 worked with developing submersible fish cages. The reason for desiring to submerge fish cages below the surface was that one experienced loss of fish fry and adult fish due to local or regional algae blooming. Ice formation on the sea surface or icing on the part of the cage construction being above the sea surface is a disadvantage. Wave action against the cages constitute a problem. On submerging the cage it will be exposed to forces being less than the forces on the sea surface. One solution is to submerge the fish cage to a level being at such a depth that the conditions are improved for the fish. The applicant has, in Norwegian patent application NO 1998.0086 xe2x80x9cSubmersible cagexe2x80x9d, filed Jan. 8, 1998, described a fish cage aranged to be submerged below the sea surface, and a method to conduct the submersion in a safe, balanced and expedient way.
NO 300 002 describes shot plates arranged in relation to the placement of a water valve in the buoyancy ring. At both sides of the shot plate air hoses are connected, being designed for both injection and exhaustion of air. Additional air hoses connected further away from the shot plate may take away air pockets during submersion.
Norwegian provisional patent NO 167 543 xe2x80x9cMethod and device to isolate the contents of a fish cagexe2x80x9d describes among others a buoyancy system to bring an outer fish cage down and under a floating cage, by means of a buoyancy ring sectioned in separate chambers. It describes shot plates and connecting valves for air and water, later described in NO 300 002.
The solution to the above mentioned problems arising in connection with the described art, is a fish cage, with one or more air-tight buoyancy rings being entirely or partially hollow, with valves for intake and outlet for water, and injection and outlet of air, and preferrably with shot plates in the buoyancy rings. The novel feature of the invention is primarily that the air valves and preferrably also the water valves are arranged inside the buoyancy rings so that they are protected against external (mechanical) acting forces.
The fish cage""s valves for connecting pressure air hoses and water valves are arranged inside the fish cage in order to make the fish cage less vulnerable to external effects.
Additional features by the invention is given in the attached subclaims.